Detection and Characterisation of Picobirnaviruses in Human and Rabbit Faeces

Human faecal samples were screened by nucleic acid extraction and polyacrylamide gel electrophoresis (PAGE) for the presence of novel dsRNA viruses. A genome typical of a bisegmented dsRNA virus termed picobirnavirus (PBV) was detected in 5 to 15% of about one thousand human faecal samples. The PBV genome consists of two equimolar segments of dsRNA of approximately 2.45 and 1.75 Kilo base pairs (Kbp) in size. During studies attempting to pass a human PBV (HPBV) strain into rabbits, a coincidental rabbit PBV (RPBV) strain was detected, and subsequently three further unique rabbit strains were detected in newly weaned rabbits. An atypical PBV (APBV) associated with Cryptosporidium positive human faecal samples was detected in 20/54 (37%) of samples. The genome of the APBV was 1.75 and 1.55 Kbp. in size and all strains detected were virtually identical. Direct electron microscopy was performed on human faecal samples and small round featureless PBV-like particles with a diameter of 35-40nm were seen. Rabbit PBV-like particles were also detected in PAGE positive CsCl gradient fractions and peaked at a buoyant density of 1.395 g/ml was obtained. An immune response temporally associated with virus excretion was demonstrated in one rabbit by immune electron microscopy. Two antigenically and genomically different strains were shown to be circulating in rabbits. Epidemiological studies to determine the prevalence of PBV in several groups of patient samples including; gastroenteritis outbreaks occurring between 1982-93, hospitalised patients, HIV-infected patients and sporadic cases of gastroenteritis, showed that PBV are widely distributed, but no association with disease was demonstrated

ensity and spectral measurements using a 34 GHz interferometry system

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76380/1/AIAA-1999-2718-743.pd

Star formation and gas inflows in the OH Megamaser galaxy IRAS03056+2034

We have obtained observations of the OH Megamaser galaxy IRAS03056+0234 using Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU), Very Large Array (VLA) and Hubble Space Telescope (HST). The HST data reveals spiral arms containing knots of emission associated to star forming regions. The GMOS-IFU data cover the spectral range of 4500 to 7500 \AA\ at a velocity resolution of 90 km s$^{-1}$ and spatial resolution of 506 pc. The emission-line flux distributions reveal a ring of star forming regions with radius of 786 pc centred at the nucleus of the galaxy, with an ionized gas mass of 1.2$\times$ 10$^{8}$M$_{\odot}$, an ionizing photon luminosity of log Q[H$^{+}$]=53.8 and a star formation rate of 4.9 M$_{\odot}$ yr$^{-1}$. The emission-line ratios and radio emission suggest that the gas at the nuclear region is excited by both starburst activity and an active galactic nucleus. The gas velocity fields are partially reproduced by rotation in the galactic plane, but show, in addition, excess redshifts to the east of the nucleus, consistent with gas inflows towards the nucleus, with velocity of $\sim$45 km s$^{-1}$ and a mass inflow rate of $\sim$7.7$\times$10$^{-3}$ M$_{\odot}$ yr$^{-1}$.Comment: To be published in MNRA

A direct image of the obscuring disk surrounding an active galactic nucleus

Active galactic nuclei (AGN) are generally accepted to be powered by the release of gravitational energy in a compact accretion disk surrounding a massive black hole. Such disks are also necessary to collimate powerful radio jets seen in some AGN. The unifying classification schemes for AGN further propose that differences in their appearance can be attributed to the opacity of the accreting material, which may obstruct our view of the central region of some systems. The popular model for the obscuring medium is a parsec-scale disk of dense molecular gas, although evidence for such disks has been mostly indirect, as their angular size is much smaller than the resolution of conventional telescopes. Here we report the first direct images of a pc-scale disk of ionised gas within the nucleus of NGC 1068, the archetype of obscured AGN. The disk is viewed nearly edge-on, and individual clouds within the ionised disk are opaque to high-energy radiation, consistent with the unifying classification scheme. In projection, the disk and AGN axes align, from which we infer that the ionised gas disk traces the outer regions of the long-sought inner accretion disk.Comment: 14 pages, LaTeX, PSfig, to appear in Nature. also available at http://hethp.mpe-garching.mpg.de/Preprint

Human bocaviruses are not significantly associated with gastroenteritis: results of retesting archive DNA from a case control study in the UK.

Gastroenteritis is a common illness causing considerable morbidity and mortality worldwide. Despite improvements in detection methods, a significant diagnostic gap still remains. Human bocavirus (HBoV)s, which are associated with respiratory infections, have also frequently been detected in stool samples in cases of gastroenteritis, and a tentative association between HBoVs, and in particular type-2 HBoVs, and gastroenteritis has previously been made. The aim of this study was to determine the role of HBoVs in gastroenteritis, using archived DNA samples from the case-control Infectious Intestinal Disease Study (IID). DNA extracted from stool samples from 2,256 cases and 2,124 controls were tested for the presence of HBoV DNA. All samples were screened in a real time PCR pan-HBoV assay, and positive samples were then tested in genotype 1 to 3-specific assays. HBoV was detected in 7.4% but no significantly different prevalence was observed between cases and controls. In the genotype-specific assays 106 of the 324 HBoV-positive samples were genotyped, with HBoV-1 predominantly found in controls whilst HBoV-2 was more frequently associated with cases of gastroenteritis (p<0.01). A significant proportion of HBoV positives could not be typed using the type specific assays, 67% of the total positives, and this was most likely due to low viral loads being present in the samples. However, the distribution of the untyped HBoV strains was no different between cases and controls. In conclusion, HBoVs, including HBoV-2 do not appear to be a significant cause of gastroenteritis in the UK population

Electromagnetic wave scattering experiments in Hall thruster plasma plumes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76740/1/AIAA-1998-3642-699.pd

Development of an Annular Helicon Source for Electric Propulsion Applications

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76441/1/AIAA-2006-4841-172.pd